These machines are used for producing various folds for formats of differing sizes (simple fold, Z-fold, roll-type fold). For this purpose, the turning direction during folding is to be reversible; even a small section of the material to be folded must be reliably held in the machine during the folding step; and the side lengths of the folded products must be freely selectable within a large range and must be simply adjustable without cumbersome mechanical alteration, solely by the regulation of the machine. In particular, folding material with inflexible components, for example staples or credit cards or samples, must be foldable without disturbances (outside of these components).
In a conventional folding machine meeting these requirements, the folding material is introduced into a flat cassette up to the location of the fold to be formed, and the cassette is turned about an axis at right angles to the feeding direction. During this step, a contact roll presses this location of the material temporarily against the rim of the cassette at which it was introduced, and thereby folds the material at this location over this rim. Subsequently, the thus-folded material is taken over, with the apex of the fold leading, by a pair of folding rollers (European Patent Application 0 059 357 A 1). The turning direction during folding is reversible by reversing the direction of rotation of the cassette; the location of the folding material to be folded can be selected by the feeding distance of the material; and the portion of the material received by the cassette can contain inflexible components without any interference in the folding procedure.
The cassette of this conventional folding machine must be equipped with transport rolls driven in one direction for receiving the folding material, being at a stand-still during rotation of the cassette, and having to be driven after the rotation in the opposite direction, in order to convey the folding material to the pair of folding rolls. This requires an expensive gear system. The drive mechanism which rotates the cassette must work very accurately so that the cassette is in alignment with the feeding direction of the folding material for the introduction of the latter and, while passing the folded material on to the pair of folding rolls, is in alignment with the plane of the folding roll nip, for this is a prerequisite for a continued conveyance of the portion of the folding material, remaining temporarily in the cassette, within its plane so that it may contain inflexible components.